ver. 0.283: Legacy class cleanup — S, Html, Email, Image, Log, Mobile_Detect → Shared namespace

- Migrate class.S → Shared\Helpers\Helpers (140+ files), remove 12 unused methods
- Migrate class.Html → Shared\Html\Html
- Migrate class.Email → Shared\Email\Email
- Migrate class.Image → Shared\Image\ImageManipulator
- Delete class.Log (unused), class.Mobile_Detect (outdated UA detection)
- Remove grid library loading from admin (index.php, ajax.php)
- Replace gridEdit usage in 10 admin templates with grid-edit-replacement.php
- Fix grid-edit-replacement.php AJAX to send values as JSON (grid.js compat)
- Remove mobile layout conditionals (m_html/m_css/m_js) from Site + LayoutsRepository
- Remove \Log::save_log() calls from OrderAdminService, ShopOrder, Order

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

autoload/Domain/Newsletter/NewsletterPreviewRenderer.php

@@ -24,7 +24,7 @@ class NewsletterPreviewRenderer
                 $articleId = (int)($article['id'] ?? 0);
                 $title = (string)($article['language']['title'] ?? '');
                 $seoLink = trim((string)($article['language']['seo_link'] ?? ''));
-                $url = $seoLink !== '' ? $seoLink : ('a-' . $articleId . '-' . \S::seo($title));
+                $url = $seoLink !== '' ? $seoLink : ('a-' . $articleId . '-' . \Shared\Helpers\Helpers::seo($title));
                 $entry = !empty($article['language']['entry'])
                     ? (string)$article['language']['entry']
                     : (string)($article['language']['text'] ?? '');